The general structure and aspect of the country may be thus described:--from Cape Leuwin to Cape Naturaliste (the southern head of Baie Géographe,) which is not quite a degree of latitude, the coast is formed of a range of hills, of uniform and moderate elevation. From Geographer's Bay to the northward of Swan River, the whole coast line is a limestone ridge, varying in height from twenty to six hundred feet, and extending inward to the distance of from one to five miles. Behind this ridge (whose occasional naked and barren appearance Captain Stirling also thinks may have caused the early and continued prejudice against the fertility of this western coast) commences a great plain, which occupies a space, from south to north, of undetermined length, (reaching, perhaps, to King George's Sound,) and varying, in breadth, from twenty to fifty miles. The eastern boundary of this plain skirts the base of an almost continuous and abrupt chain of mountains, to which Captain Stirling gave the name of "General Darling's Range." One of the points, the highest seen and measured by him, was about three thousand feet high, The average height is stated to be from twelve hundred to fifteen hundred feet. The base is granite; the sides, in many parts, naked; and the soil supports but little vegetation, except the Stringy-bark and some hardy plants.
Captain Stirling observes, that coal was not found, because it was not particularly sought for; but he is of opinion that the general character of the country is such as to warrant the belief that it might be found; "for," he observes, "all the concomitant strata or members of the coal formation are exposed on different parts of the surface, below which I had no opportunity to explore. Indeed, the carboniferous order of locks is that which is most frequently exhibited throughout this territory; and I have no doubt important results would arise from a proper examination into its mineralogical resources."
With reference to a supply of fresh water, so indispensably necessary in every settled country, the researches made by Captain Stirling and Mr. Fraser were attended with the most satisfactory results. The former observes, that the clouds which are impelled against the western side of the range of mountains are condensed into rain, the water of which is conducted across the plain to the sea, in numerous streams, but chiefly by three principal rivers, terminating in estuaries, or salt-water lakes. These are--the Swan River, opposite the Island Rottenest; the Rivière Vasse, and Port Leschenault, in Geographer's Bay. "We found," says Captain Stirling, "a great number of creeks, or rivulets, falling into Swan River, more particularly on the eastern side; and I am inclined to think, that the country generally is much divided by such water-courses. Its supply of fresh water, from springs and lagoons, is abundant; for we found such wherever we thought it necessary to ascertain their existence. At Point Heathcote," he adds, "we met with a remarkable instance; for there the beach of a narrow rocky promontory is a bed of springs, and by tracing the finger along any part within four inches of the edge of the salt water, pure and fresh water instantly occupied the trace."